Cooling Schemes And Methods For Cooling Tower Motors

ABSTRACT

The present invention provides techniques, schemes configurations and methods for removing or reducing heat in motors. In one embodiment, the present invention is directed to a cooling tower comprising a cooling tower structure and a motor supported by the cooling tower structure. The motor comprises a motor casing and a rotatable shaft. The cooling tower further comprises a cooling tower fan that comprises a fan hub, a plurality of fan blades attached to the rotatable shaft and a supplemental fan attached to the fan hub such that the supplemental fan is between the fan hub and the motor. Rotation of the cooling tower fan causes rotation of the supplemental fan which increases airflow around the casing of the motor so as to facilitate cooling of the motor. Other embodiments of configurations, schemes, method and techniques for thermally managing motors are described herein in detail.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. applicationno. 62/027,100, filed Jul. 21, 2014 and to U.S. application no.62/049,105, filed Sep. 11, 2014. The entire disclosures of the aforesaidU.S. application nos. 62/027,100 and 62/049,105 are hereby incorporatedby reference.

TECHNICAL FIELD

The present invention is directed to various schemes and configurationsfor cooling electric machines having a stator and rotor that thatproduce flux, such as electric motors.

BACKGROUND ART

During operation of electric machines having a stator and a rotor, suchas motors, excessive heat may be generated in the stator windings or inother portions of the electric machine. In order to prevent suchexcessive heat from damaging the electric machine, reducing itsperformance or shortening its operational life, it is necessary to coolthe motor so as to reduce or remove the heat. The aforementioned problemwith excessive heat is a significant problem in motors used in coolingtowers or air-cooled heat exchangers.

DISCLOSURE OF THE INVENTION

The present invention provides techniques, schemes configurations andmethods for removing or reducing heat in electrical machines having astator and rotor that cooperate to produce flux. In particular, thepresent invention provides techniques, schemes configurations andmethods for removing or reducing heat in motors that are used in coolingtowers or air-cooled heat exchanger towers.

In one embodiment, the present invention is directed to a cooling towercomprising a cooling tower structure and a motor supported by thecooling tower structure. The motor comprises a motor casing and arotatable shaft. The cooling tower further comprises a cooling tower fanthat comprises a fan hub, a plurality of fan blades attached to therotatable shaft and a supplemental fan attached to the fan hub such thatthe supplemental fan is between the fan hub and the motor. Rotation ofthe cooling tower fan causes rotation of the supplemental fan whichincreases airflow around the casing of the motor so as to facilitatecooling of the motor.

Other embodiments of configurations, schemes, method and techniques forthermally managing motors are described herein in detail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a portion of a wet cooling tower.

FIG. 2 is a bottom view of a cooling tower fan having a supplemental fanin accordance with one embodiment of the invention;

FIG. 3 is a side view of the cooling tower fan having a supplemental fanin accordance with another embodiment of the invention, the view showingonly a portion of the cooling tower fan in order to emphasize thesupplemental fan;

FIG. 4A is a side view of the cooling tower fan having a supplementalfan in accordance with another embodiment of the invention

FIG. 4B is a side view of the cooling tower fan having a supplementalfan in accordance with another embodiment of the invention;

FIG. 4C is a side view of the cooling tower fan having a supplementalfan in accordance with another embodiment of the invention, the viewshowing only a portion of the cooling tower fan in order to emphasizethe supplemental fan;

FIG. 5A is a side elevational view, partially in cross-section, of aTotally Enclosed Fan Cooled Motor having an elliptical traction drivedevice;

FIG. 5B is plan view of the elliptical traction drive device shown inFIG. 5A;

FIG. 6 is a side elevational view, partially in cross-section, of aTotally Enclosed Fan Cooled Motor having an elliptical traction drivedevice in accordance with another embodiment of the invention;

FIGS. 7A-F are partial, elevational views of various cooling tubes usedin the motors of the present invention

FIG. 8A is a diagram of a motor using a passive air-cooling scheme inaccordance with one embodiment of the invention;

FIG. 8B is a plan view of the stator of the motor of FIG. 8A, the viewnot showing other motor components in order to simplify the view of thestator;

FIG. 9A is a diagram of a motor using a passive air-cooling scheme inaccordance with one embodiment of the invention;

FIG. 9B is a plan view of the stator of the motor of FIG. 9A, the viewnot showing other motor components in order to simplify the view of thestator

FIG. 10A is a diagram of a motor using a passive air-cooling scheme inaccordance with one embodiment of the invention;

FIG. 10B is a plan view of the stator of the motor of FIG. 10A, the viewnot showing other motor components in order to simplify the view of thestator.

FIG. 11 is a diagram of a motor in accordance with another embodiment ofthe invention;

FIG. 12A is a diagram of a motor in accordance with another embodimentof the invention;

FIG. 12B is a plan view of the stator of the motor of FIG. 12A, the viewnot showing other motor components in order to simplify the view of thestator;

FIG. 13A is a diagram of a motor in accordance with another embodimentof the invention;

FIG. 13B is a plan view of the stator of the motor of FIG. 13A, the viewnot showing other motor components in order to simplify the view of thestator;

FIG. 14A is a diagram of a motor in accordance with another embodimentof the invention;

FIG. 14B is a plan view of the stator of the motor of FIG. 14A, the viewnot showing other motor components in order to simplify the view of thestator;

FIG. 15A is a diagram of a motor in accordance with another embodimentof the invention, the view only showing half of the motor in order tosimplify the view of the novel features of the motor;

FIG. 15B is a diagram of a motor in accordance with another embodimentof the invention, the view only showing half of the motor in order tosimplify the view of the novel features of the motor;

FIG. 16 is a diagram of a motor in accordance with another embodiment ofthe invention, the view only showing half of the motor in order tosimplify the view of the novel features of the motor;

FIG. 17 is a side view, in elevation, of a motor in accordance withanother embodiment of the invention;

FIG. 18A is plan view of a stator in accordance with another embodimentof the invention;

FIG. 18B is a diagram of the serpentine cooling tubes used in the statorof FIG. 18A;

FIG. 19A is a diagram of a motor in accordance with another embodimentof the invention;

FIG. 19B is a plan view of the stator of the motor of FIG. 19A, the viewnot showing other motor components in order to simplify the view of thestator;

FIG. 20A is a diagram showing stator windings wrapped about a coolingtube;

FIG. 20B is a diagram showing an electrically insulative layer ofmaterial wrapped about a cooling tube, stator windings wrapped about theelectrically insulative layer of material and an additional electricallyinsulative layer wrapped about the stator windings;

FIG. 21A is a diagram of a motor in accordance with another embodimentof the invention;

FIG. 21B is a plan view of the stator of the motor of FIG. 19A, the viewnot showing other motor components in order to simplify the view of thestator; and

FIG. 21C is a plan view of a heat pipe and heat sink shown in FIG. 21A.

BEST MODE FOR CARRYING OUT THE INVENTION

It is well known in the industry that motors have “housings” or“casings” that contain the internal components in the motor, such as thestator and rotor. As used herein, the terms “casing” or “motor casing”,“housing” or “motor housing” all have the same meaning and are usedinterchangeably.

Although the ensuing description is in terms of the embodiments of thepresent invention being used in a cooling tower or air-cooled heatexchanger, it is to be understood that the ensuing embodiments of thepresent invention may be applied to motors used in applications otherthan cooling towers or air-cooled heat exchangers.

Wet cooling towers are described in U.S. Pat. No. 8,111,028 entitled“Integrated Fan Drive System For Cooling Tower” and internationalapplication no. PCT/US2012/061244 entitled “Direct Drive Fan System WithVariable Process Control” and published under International PublicationNo. WO 2013/059764. The entire disclosure of U.S. Pat. No. 8,111,028 ishereby incorporated by reference. The entire disclosure of internationalapplication no. PCT/US2012/061244 is hereby incorporated by reference.Dry cooling towers are described in U.S. Pat. No. 8,188,698 entitled“Integrated Fan Drive System For Air-Cooled Heat Exchanger (ACHE)”. Theentire disclosure of U.S. Pat. No. 8,188,698 is hereby incorporated byreference.

The present invention is directed to various methods, techniques,configurations and schemes for cooling motors and to corresponding motorconfigurations. In accordance with the invention, various coolingmediums are used to cool the motors. Such cooling mediums include clean,dry, filtered air and water, or a combination of clean, dry, filteredair and water, or a combination of clean, dry, filtered air and watermixed with additives such as glycol, ammonia or Freon. Another coolingmedium used is chilled air which may be compressed. In otherembodiments, a gas or combination of gases are used instead of air.

Although the ensuing description is in terms of the embodiments of theinvention being applied to wet cooling towers, it is to be understoodthat embodiments of the invention may be applied to dry cooling towersor ACHE units as disclosed in the aforementioned U.S. Pat. No.8,188,698. It is also to be understood the embodiments of the inventionmay be applied to a motor regardless of it orientation (e.g. upsidedown, right side up, angular orientation, horizontal, etc.). Thus, thetechniques, schemes, configurations and methods of the present inventionmay be applied to a motor regardless of the orientation of its shaft.

Referring to FIG. 1, there is shown a basic block diagram of coolingtower 15 that utilizes motor 20 of the present invention. Cooling tower15 includes fan stack 22, fan deck 24 and fan 26. Fan stack 22 isconnected to fan deck 24. Fan 26 has fan hub 28 and fan blades 29 thatare connected to fan hub 28. Motor 20 has rotatable shaft 100 thatdirectly drives fan 26. Fan 26 rotates within fan stack 22. Motor 20includes casing 30 which has exterior surface 32. The height of motor 20must be in a predetermined range in order to maintain the height of fan26 in fan stack 22 for sealing and fan performance. Motor 20 isrelatively large in diameter in order to produce a significant torque tocause rotation of fan 26. Cooling tower 20 is a “wet cooling tower”which uses the latent heat of evaporation to cool process fluids.“Process fluids” are fluids that are used in a process, e.g. crackingcrude, chemical processing, etc. Since motor 20 is directly driving thefan, the air-flow around motor 20 is relatively low.

The air-flow around motor 20 is dictated by the diameter of the fan hub,fan blades and fan speed. It has been found that making the fan hubdiameter smaller and extending the fan blade to the smaller diameter fanhub increases the air flow around the motor.

Referring to FIG. 2, in order to increase the air-flow around motor 20,supplemental fan 50 is connected to the bottom side 28A of fan hub 28.Fan 50 comprises hub 52 and blades 54 that are attached to hub 52. Inorder to simplify the view of FIG. 2, fan blades 29 are not shown inFIG. 2. The function of fan 50 is to draw more airflow around motor 20wherein the increased air-flow can be used to cool motor 20. Althoughfan 26 is a multi-piece fan, it is to be understood the fan 50 can beconnected to a one-piece fan as well as relatively smaller fans such asthe BAC Whisper Quiet Fan. The particular type, design, size and weightof fan 50 depends upon the type of installation required, fan speed, therequired air flow for the motor and whether the motor is a single speedor variable speed motor.

Referring to FIG. 3, there is shown another embodiment of the invention.Supplemental fan 60 is attached or connected to the bottom 28A of fanhub 28. Fan 60 comprises fan blades 62. In one embodiment, supplementalfan 60 is a separate component that is connected or attached to fan hub28. In another embodiment, fan 60 is integral with fan 28. In otherembodiments, fan 60 may be connected to a one-piece fan as well as tosmaller fans such as the BAC Whisper Quiet Fan. In another embodiment,fan 60 is configured to have a variable pitch apparatus to providevarious fan pitch to fan 60 for various air-flows.

Referring to FIG. 4A, there is shown another embodiment of the presentinvention. Supplemental wide chord fan blade 70 is attached or connectedto fan blade 29 (see FIG. 1) in order to increase air-flow to motor 20.Adjustable pitch device 72 is either a separate component that isattached fan blade 29 or is integrally formed with fan blade 29.Adjustable pitch device 72 allows for adjustment of the pitch ofsupplemental wide chord fan blade 70. It is to be understood that asupplemental wide chord fan blade 70 can be attached to each fan blade29.

Referring to FIG. 4B, there is shown another embodiment of the presentinvention. Fan pitch adjustment device 80 is attached to the neck of fanblade 29 and supplemental wide chord fan blade 82 is connected to pitchadjustment device 80. Pitch adjustment device 80 allows for theadjustment of the pitch of supplemental wide chord fan blade 82. It isto be understood that a supplemental wide chord fan blade 82 can beattached to each fan blade 29.

Referring to FIG. 4C, there is shown another embodiment of the presentinvention. In this embodiment, adjustable fan pitch devices 90 areeither integral with fan hub 28 or are separate components that areattached to bottom side 28A of fan hub 28. A supplemental fan blade 92is attached to each adjustable fan pitch device 90.

Some motors, due to their design, rotate the cooling fan too slow forthe cooling fan to produce an appreciable cooling flow. For example, fanspeeds below 200 RPM may not generate any appreciable air-flow aroundthe motor. In order to solve this problem, the motor 100, shown in FIGS.5A, 5B and 6, is presented. Totally Enclosed Fan Cooled (TEFC) motor 100comprises casing 102, shaft 104 and a stator and rotor (not shown). Inorder to increase fan speed, motor 100 comprises an Elliptical TractionDrive (ETD) device 110. Elliptical Traction Drive device 110 comprisesoutput ring roller 112, sun roller 114 and star rollers 116. ETD device110 includes shaft 118 that is connected to the cooling tower fan. Sunroller 114 is integral with motor shaft 104. ETD 110 can step up or stepdown the fan speed as required for cooling with respect to fan design.Such an ETD device 110 is described in international application no.PCT/US2014/014408, entitled “Direct-Drive System For Cooling SystemFans, Exhaust Blowers And Pumps”, published under internationalpublication no. WO 2014/123804, and is therefore not described in detailherein. The entire disclosure of international application no.PCT/US2014/014408 is hereby incorporated by reference. Thus, motor 100can replace motor 20 shown in FIG. 1. Furthermore, motor 100 can be usedwith fan 26 as modified with any of supplemental fans shown in FIGS. 2,3 and 4A-C.

Referring to FIG. 6, there is shown an alternate TEFC motor 150 inaccordance with another embodiment of the invention. Motor 150 includescasing 152, rotational shaft 154 and ETD device 160. ETD device 160 islocated at the bottom of motor 150. Supplemental axial fan 170 ismounted to ETD device 160 with a modified mounting arrangement andwithout the enclosure. Supplemental axial fan 170 provides additionalcooling of motor 150.

In another aspect of the invention, a motor may be configured to includecooling tubes having particular configurations such as cooling fins,radial fins, oval holes, round holes, round tubes, and thumbnails inorder to effect cooling of the motor. Such cooling tube configurationsare shown in FIGS. 7A-F. FIG. 7A shows cooling tube 200 havinglongitudinal fins 202. In a preferred embodiment, cooling tube 200 is acontinuous tube. Cooling tube 200 can transfer air and/or water from onelocation in the motor to another location in the motor without leakageand exchange heat between the motor and the media in cooling tube 200.FIG. 7C shows cooling tube 212 having radial fins 214. In a preferredembodiment, cooling tube 212 is a continuous tube. The cooling tube 212transfers air and/or water from one location in the motor to anotherlocation in the motor. Cooling tube 212 exchanges heat between the motorand the media in cooling tube 212. FIG. 7D shows round cooling tube 216having a smooth configuration. In a preferred embodiment, cooling tube216 is a continuous tube with a smooth surface. The cooling tube 216transfers air and/or water from one location in the motor to anotherlocation in the motor without leakage and exchanges heat between themotor and the media in cooing tube 216. FIG. 7B shows cooling tube 210that has round holes 211. FIG. 7E shows cooling tube 218 having ovalholes 220. FIG. 7F shows a cooling tube 222 that is configured withthumbnails 224. In preferred embodiments, cooling tubes 210, 218 and 222are continuous tubes that transfer air and/or water from one location inthe motor to another location in the motor without leakage and exchangesheat between the motor and the media in the cooling tube.

In alternate embodiments, the cooling tubes shown in FIGS. 7A-F may bemodified to have other cross-sectional shapes.

In another embodiment, air from the cooling tubes is forced throughround and/or oval holes and/or thumbnails into the motor cavityimparting swirl and turbulence that facilitates mixing of hot and coldair to improve heat transfer.

Referring to FIGS. 8A and 8B, there is shown motor 250 that incorporatesa passive air-cooling scheme in accordance with one embodiment of thepresent invention. Motor 250 comprises casing 252, top cover 254, bottomcover 256, rotor 258, rotatable shaft 260 and stator 300. Rotor 258includes a plurality of permanent magnets 259. Stator 300 comprises aplurality of lamination sheets 302 that are attached or bonded togetherto form stack 304. Each lamination sheet 302 has a plurality of slots306 through which windings or coils 308 are wound. During operation ofmotor 250, significant heat is produced in windings 308. In accordancewith this embodiment of the invention, round, continuous cooling tubes310 are inserted into the windings or coils 308 in order to directlycool windings 308 and facilitate transfer of heat from windings 308 tothe outside environment. Cooling tube 310 has the same configuration ascooling tube 216 shown in FIG. 7D. Cooling tubes 310 are sealed at topcover 254 with O-ring 320 and at bottom cover 256 with O-ring 322.O-ring 320 prevents moisture or contaminants enter motor 250 at thejunction of tubes 310 and top cover 254. Similarly, O-ring 322 preventsmoisture or contaminants from entering motor 250 at the junction oftubes 310 and bottom cover 256. O-rings 320 and 322 allow for thermalexpansion of motor 250 and maintain sealing integrity. Each tube 310 hasbottom opening 330 that is in communication with a corresponding openingin bottom cover 256. Each tube 310 also has a top opening 332 incommunication with a corresponding opening in top cover 254. Cooling airflows into bottom opening 330 and flows through the tube 310 and isejected from top opening 332 into the fan air stream. This coolingembodiment takes advantage of the available upward moving air under andaround motor 250 created by rotation of the direct-drive cooling towerfan or supplemental fan. For a wet cooling tower, the 100% humid airfacilitates removal of heat from windings 308. In one embodiment,cooling tubes 310 are fabricated from copper. In one embodiment, coolingtubes 310 are insulated with Teflon, Silicone or an equivalent materialfor windings 308. Teflon offers the advantage of temperaturecompatibility with the benefit of suitable electrical insulatingproperties. Silicone offers excellent thermal conductivity combined withexcellent electrical insulating properties. If cooling tubes 310 aremade from copper and/or other electrically conductive materials, thenthe cooling tubes 310 will have to be electrically insulated. However,if windings 308 have been through a Vacuum Pressure Impregnated (VPI)Process, the additional electrical insulation may not be necessary.Cooling tubes 310 may be manufactured from other materials that arethermally conductive and electrically insulative such as Teflon,silicone and high temperature plastics. In an alternate embodiment, acooling tube 310 is embedded in every other winding 308.

Rotor 258 includes fan structure 375 that is attached to or integralwith the top end of rotor 258 and fan structure 376 that is attached toor integral with the bottom end of rotor 258. Fan structures 375 and 376have the same structure, function and purpose as fan structures 850 and852, respectively, that are shown in FIG. 13A and described herein.

Cooling tubes are best used at the source of the generated heat sourcesuch as the coil, but are not limited to those locations. It is to beunderstood that the cooling tube route may be varied as required byapplication and is not limited to configuration wherein the coolingtubes extend between the top and bottom covers of the motor casing.

Referring to FIGS. 9A and 9B, there is shown motor 400 whichincorporates a passive air-scheme in accordance with another embodimentof the invention. Motor 400 comprises casing 401, top cover 402, bottomcover 403, rotor 404, rotatable shaft 406 and stator 408. Rotor 404includes a plurality of permanent magnets 409 as is well known in theart. Stator 408 comprises a plurality of lamination sheets 410 that areattached or bonded together to form stack 412. Each lamination sheet 410has a plurality of slots 411 (similar to 306 in FIG. 8A) through whichwindings or coils 414 are wound. During operation of the motor,significant heat is produced in windings 414. In this embodiment, stator408 does not use round cooling tubes. Instead, continuous ducts 420 areembedded in stator 408 as windings 414 are inserted into the statorstack 412 during production of stator stack 412. Each duct 420 may havea unique shape other than circular. Each duct 420 has a bottom opening422 that is in communication with a corresponding opening in bottomcover 403. Each duct 420 also has a top opening 424 in communicationwith a corresponding opening in top cover 402. Cooling air flows intobottom opening 422 of each duct 420 and flows through the ducts 420 andis ejected from top opening 424 into the fan air stream. This passivecooling air-cooling embodiment is suited for use in relativelarge-diameter direct-drive cooling tower motors, such as motor 400,since such motors are configured with a “pancake motor arrangement”wherein the motor is relatively short in height as required byinstallation purposes. Motor 400 has relatively large deep slotlaminations 410 that make up stator 408 thereby allowing for extra roomfor ducts 420 to pass air to cool coils windings 414. When combined withdeep slot laminations, the shaped ducts 420 can be installed between theinserted windings 414, which are near casing 401, and rotor 404 therebyproviding an insulating barrier of air that prevents or minimizes thetransfer of heat from the windings to the magnets that are on rotor 404.O-rings 450 seal the junction of ducts 420 and top cover 402 and O-rings460 seal the junction of ducts 420 and bottom cover 403 in the samemanner in which cooling tubes 310 are sealed to top cover 254 and bottomcover 256 (see FIGS. 8A and 8B).

Rotor 404 comprises fan structure 480 that is attached to or integralwith the top end of rotor 404 and fan structure 482 that is attached tothe bottom end of rotor 404. Fan structures 480 and 482 have the samestructure, function and purpose as fan structures 850 and 852,respectively, that are shown in FIG. 13A and described herein.

Referring to FIGS. 10A and 10B, there is shown motor 500 which uses analternate passive air-cooling scheme in accordance with anotherembodiment. In this embodiment, motor 500 comprises casing 502, rotor504, rotatable shaft 506, stator 508 bottom cover 509 and top cover 510.Rotor 504 has a plurality of magnets 511 attached thereto as is wellknown in the art. Stator 508 comprises a plurality of lamination sheets517 that are attached or bonded together to form stator stack 512. Eachlamination sheet 517 has a plurality of slots 519 through which windingsor coils 514 are wound. Stator 508 is configured exactly the same asstator 300 in (see FIGS. 8A and 8B) and uses cooling tubes 515. Coolingtubes 515 have the same shape, configuration and functions as coolingtubes 310. Motor 500 includes inlet ducts 520 and 522 that are mountedor attached to bottom cover 509. Motor 500 further includes exhaustnozzles 530 and 532 that are mounted or attached to top cover 510. Inletducts 520, 522 and output nozzles 530, 532 are in communication withcooling tubes 515. Air-flow, indicated by reference number 540, flowsinto inlet ducts 520 and 522 and through cooling tubes 515 and then outthrough exhaust nozzles 530 and 532. Inlet ducts 520, 522 and outputnozzles 530, 532 enhance the flow of air into cooling tubes 515. Inletducts 520 and 522 direct more available air (and water) into coolingtubes 515 and out through exhaust nozzles 530 and 532 so as tofacilitate acceleration of air back into the fan airstream throughcontrolled expansion. As a result of this configuration, mass airflowthrough cooling tubes 515 is improved thereby increasing heat transfer.

Rotor 504 comprises fan structure 575 that is attached to or integralwith the top end of rotor 504 and fan structure 576 that is attached toor integral with the bottom end of rotor 504. Fan structures 575 and 576have the same structure, function and purpose as fan structures 850 and852, respectively, that are shown in FIG. 13A and described herein.

Referring to FIG. 11, there is shown motor 600 that incorporates apassive air-cooling embodiment in accordance with another embodiment ofthe invention. Motor 600 comprises casing 602, rotor 604, shaft 605 andstator 606. Rotor 604 includes a plurality of magnets 650. Stator 606has the same configuration as stator 408 (see FIG. 9B). Thus, stator 606comprises continuous ducts 607 which are the same as continuous ducts420 used in stator 408. Motor 600 further comprises top cover 613 andbottom cover 615. In this embodiment, motor 600 has relatively largerinlet ducts 610 and 612 that are mounted or attached to bottom cover 615and in communication with the continuous ducts 607 embedded in stator606. Inlet ducts 610 and 612 channel airflow 614 into the continuousducts 607 embedded in stator 606. The air flowing into the continuousducts 607 flows out through exhaust nozzles 616 and 618 which aremounted or attached to top cover 613.

Rotor 604 comprises fan structure 675 that is attached to or integralwith the top end of rotor 604 and fan structure 676 that is attached toor integral with the bottom end of rotor 604. Fan structures 675 and 676have the same structure, function and purpose as fan structures 850 and852, respectively, that are shown in FIG. 13A and described herein.

In alternate embodiments of the invention, the cooling tubes of FIGS.8A, 8B, 10A and 10B and continuous ducts of FIGS. 9A, 9B and 11 aresealed at both ends with a phase change material between the sealedends. The phase change material may include solids, liquids, gases orany combination thereof which effects meets thermal mass requirements tocool and heat the motor. Suitable phase change material is described inU.S. Pat. No. 4,459,949 entitled “Liquid Metal Cooled InternalCombustion Engine Valves With Getter”, the disclosure of which patent ishereby incorporated by reference.

Referring to FIGS. 12A and 12B, there is shown motor 700 in accordancewith another embodiment of the present invention. Motor 700 comprisescasing 702, top cover 703, bottom cover 704, stator 705, rotor 706 androtor shaft 708. Rotor 706 includes a plurality of permanent magnets709. In this embodiment, stator 705 has the same configuration andstructure as stator 508 shown in FIGS. 10A and 10B. Thus, stator 705includes cooling tubes 710 which have the same shape and configurationas cooling tubes 515. Cooling tubes 710 are embedded in the slots of thestator stack as winding 712 are inserted into the stack. Cooling tubes710 are in communication with the external environment of motor 700.Motor 700 includes manifold 720 that is attached to bottom cover 704.Manifold 720 has intake port 722 that receives air from an air source.One such example of a suitable air source is a blower that is locatedoutside the fan stack of the cooling tower. Manifold 720 may be aseparate assembly or integral with bottom cover 704. Manifold 720receives the pressurized air from the air-source outside of the fanstack and distributes the pressurized air into cooling tubes 710. Thepressurized air 730 is ejected into the fan airstream by cooling tubes710.

Rotor 706 comprises fan structure 750 that is attached to or integralwith the top end of rotor 706 and fan structure 752 that is attached toor integral with the bottom end of rotor 706. Fan structures 750 and 752have the same structure, function and purpose as fan structures 850 and852, respectively, that are shown in FIG. 13A and described herein.

In embodiments in which stator 705 uses continuous cooling tubesconfigured as cooling tube 216 shown in FIG. 7D, the pressurized aircould be regular filtered air from a blower or compressor. Thepressurized air would be ejected into the surrounding environment in amanner similar to the embodiments shown in in FIGS. 8A, 8B, 9A and 9B.This embodiment would allow the pressurized air to be either cooled orheated. Cooled air may be supplied from a chiller or a Transvector Jetby Vortec installed in-line with the air source that is outside of thefan stack. Heating of the air also prevents freezing in colder climates.

In alternate embodiments, tubes or ducts having holes therein areembedded in the stator. These embodiments would be used with filtered,clean dry air because the motor is sealed by design and must remainclean of contamination and moisture. The addition of an exhaust nozzle,as show in FIGS. 10A and 11 would enhance the mass flow of air. In analternate embodiment, exhaust nozzles are replaced or combined withflapper valves or equivalent to seal the motor from contamination.Grainger filters can be combined with flapper valves or equivalent.

Referring to FIGS. 13A and 13B, there is shown motor 800 in accordancewith another embodiment of the invention. Motor 800 comprises casing802, top cover 803, bottom cover 804, stator 805, rotor 806 and rotorshaft 808. Rotor 806 has a plurality of permanent magnets 809. In thisembodiment, stator 805 has the same configuration and structure asstator 508 shown in FIGS. 10A and 10B. Thus, stator 805 includes coolingtubes 810 which have the same shape and configuration as cooling tubes515. Cooling tubes 810 are in communication with the externalenvironment of motor 800. Motor 800 includes inlet manifold 820 that isattached to bottom cover 804. Manifold 820 has intake port 822 thatreceives clean, dry, filtered air from an air source that is locatedoutside of the fan stack. Suitable air sources include a blower,chiller, heater, compressor, recirculation system, heat exchanger, orcombinations thereof. Manifold 820 may be a separate assembly orintegral with bottom cover 804. Manifold 820 receives pressurized airfrom the air-source outside of the fan stack and distributes thepressurized air into cooling tubes 810. Motor 800 further includesoutlet manifold 830 that is attached to top cover 803. Outlet manifold830 receives the pressurized air flowing through cooling tubes 810 anddischarges the air 840 outside the fan stack with corresponding piping(not shown).

As shown in FIG. 13A, rotor 806 includes fan structure 850 attached tothe top end of rotor 806 and fan structure 852 that is attached to thebottom end of rotor 806. Fan structure 850 includes a plurality ofblades or vanes. Similarly, fan structure 852 includes a plurality ofblades or vanes. As rotor 806 rotates, fan structures 850 and 852 mixthe air around the magnets on rotor 806 and mix the air within theinterior of the motor in order to create a heat path from the rotor 806to casing 802. This configuration causes a transfer of heat from rotor806 to casing 802.

In another embodiment, each cooling tube 810 is configured to have holestherein to deliver dry, clean, filtered air into the motor cavity whichmixes with existing air inside the motor cavity by fan structures 850and 852 so as to (i) provide heat transfer of either hot or cold air,(ii) collect any moisture within the motor cavity, and (iii) exhaustthat air through outlet manifold 830. Outlet manifold 830 discharges theair outside of the fan stack. In one embodiment, outlet manifold 830discharges the air to a filter that is located outside of the fan stack.One example of such a filter is the Grainer Part Number 3TLA2. Thisembodiment not only provides thermal management of the motor withheating and cooling options but also provides thermal and motor volumeexpansion management to maintain motor operating clearances such asrotor-to-stator clearance. This embodiment also maintains sealingintegrity and prevents overheating of the motor, especially thetemperature sensitive magnets, and prevents freezing of the motor incolder climates. This embodiment allows the use of smaller auxiliarycooling systems that are less costly but highly effective, have smallerfootprints and weigh less for places such as cooling towers andskyscrapers that have weight and other structural limitation relative tosize and weight. The cooling tubes may be treated with a suitable heatdissipation coating.

In an alternate embodiment, cooling tubes 810 are replaced withcontinuous ducts of the type shown in FIG. 9B. In one embodiment, thecontinuous ducts do not have holes therein so that air in the duct doesnot enter the motor cavity. In another embodiment, the continuous ductshave holes therein to allow air to enter the motor cavity for thereasons stated in the foregoing description.

The cooling tubes and ducts can be custom designed to have variousshapes, routings and volumes and may be formed to fit into the availablestator lamination slot and other available space in the motor in orderto maximize heat transfer from the motor.

In further embodiment, solid tubes are used in stator 805. The solidtubes conduct heat and remove the heat in a manner similar to a radiatoror tubes that have various hole configurations that can input airdirectly to the inside of the motor cavity.

Referring to FIGS. 14A and 14B, there is shown another embodiment of theinvention. Motor 900 comprises casing 902, top cover 903, bottom cover904, stator 905, rotor 906 and rotor shaft 908. Rotor 906 includes aplurality of magnets 909. In this embodiment, stator 905 has the sameconfiguration and structure as stator 508 shown in FIGS. 10A and 10B.Thus, stator 905 includes cooling tubes 910 which have the same shapeand configuration as cooling tubes 515. Motor 900 includes inletmanifold 920 that is attached to bottom cover 904. Manifold 920 hasintake port 922 that receives clean, dry, filtered air from an airsource that is located outside of the fan stack. Suitable air sourcesinclude a blower, chiller, heater, compressor, recirculation system,heat exchanger, or combinations thereof. Manifold 920 may be a separateassembly or integral with bottom cover 904. Cooling tubes 910 are incommunication with manifold 920. Manifold 920 receives pressurized airfrom the air source located outside of the fan stack and distributes theair into cooling tubes 910. Motor 900 further includes outlet manifold930 that is attached to top cover 903. Cooling tubes 910 are incommunication with outlet manifold 930. Outlet manifold 930 receives thepressurized air flowing through cooling tubes 910 and discharges thisair through discharge filter 950 which is connected to outlet manifold930. In one embodiment, discharge filter 950 has operatingcharacteristics similar to Grainer Part Number 3TLA2 or an equivalentPall PFD filter. Discharge filter 950 ejects air into the air streamwithin the fan stack. In another embodiment, discharge filter 950 ejectsair outside the fan stack via additional piping or duct work.

In an alternate embodiment, discharge filter 950 is replaced or combinedwith a flapper valve or equivalent device to prevent contamination andmoisture from entering the motor when pressurize air is not present.

In another embodiment, outlet manifold 930 is not used and cooling tubes910 eject the air directly into an exit filter that is mounted to topcover 903. Such an embodiment is suitable when the direction of air isfrom top to bottom (see FIG. 1).

In an alternate embodiment, cooling tubes 910 are replaced withcontinuous ducts of the type shown in FIGS. 9A and 9B.

In other embodiments, cooling tubes 910 are replaced with any of thecooling tubes shown in FIGS. 7A-C, 7E and 7F. In a further embodiment,cooling tubes 910 are replaced with any combination of the cooling tubesshown in FIGS. 7A-C, 7E and 7F.

Rotor 906 comprises fan structure 960 that is attached to or integralwith the top end of rotor 906 and fan structure 962 that is attached toor integral with the bottom end of rotor 906. Fan structures 960 and 962have the same structure, function and purpose as fan structures 850 and852, respectively, that are shown in FIG. 13A and described herein.

Referring to FIG. 15A, there is shown a partial view of motor 1000 inaccordance with another embodiment of the present invention. Motor 1000comprises casing 1002, top cover 1004 which is attached to casing 1002,bottom cover 1005 which is attached to casing 1002, stator 1006, rotor1008 and rotatable shaft 1010 which is connected to rotor 1008. Rotor1008 includes permanent magnets 1011. In this embodiment, stator 1006does not utilize continuous cooling tubes or ducts as described in theforegoing description. Motor 1000 further comprises intake manifold1010. In one embodiment, intake manifold 1010 is a separate assemblythat is connected to bottom cover 1004. In another embodiment, intakemanifold 1010 is integral with bottom cover 1004. Pressurized, clean,dry, filtered air is provided to the intake port (not shown) of manifold1010 which then delivers this air into the motor cavity. Motor 1000further comprises outlet manifold 1020 which collects the air out of themotor cavity and ejects the air into the fan stack or outside the fanstack. This is a continuous process wherein pressurized, clean, dry,filtered air is delivered to the motor cavity by intake manifold 1010,the delivered air absorbs heat of the motor components and then theheated air is ejected from the motor 1000 by outlet manifold 1020. Inalternate embodiments, discharge filters can be used with the outletmanifold 1020.

Referring to FIG. 15A, rotor 1008 includes fan structure 1050 that isattached to or integral with the top end of rotor 1008 and fan structure1052 that is attached to or integral with the bottom end of rotor 1008.Fan structures 1050 and 1052 have the same structure, function andpurpose as fan structures 850 and 852, respectively, that are shown inFIG. 13A and described herein.

Referring to FIG. 15B, there is shown another embodiment of theinvention. Motor 1200 comprises casing 1202, top cover 1204 which isattached to casing 1202, bottom cover 1205 which is attached to casing1202, stator 1206, rotor 1208 and rotatable shaft 1210 which isconnected to rotor 1208. Rotor 1208 has fan structures 1212 and 1214attached thereto which have the same structure and function as fanstructures 850 and 852 shown in FIG. 13A. In this embodiment, stator1206 does not utilize continuous cooling tubes or ducts as described inthe foregoing description. Motor 1200 further comprises air input port1220 which receives air from an air source located outside the fanstack. One example of a suitable air source is a blower. In oneembodiment, air input port 1220 is an air inlet duct. Air input port1220 may be a separate component or it may be integral with bottom cover1205. Motor 1200 includes air outlet port 1222 on top cover 1204. Airoutlet port 1222 can either be a separate component or it can beintegral with top cover 1204. Air input port 1220 delivers thepressurized, clean, dry, filtered air into the motor cavity wherein thedelivered air is mixed with the air in the motor cavity by fanstructures 1212 and 1214 so as to provide heat transfer and moisturecontrol. The heated pressurized air then leaves the motor cavity via airoutlet port 1222 wherein it is discharged outside the fan stack. In analternate embodiment, a discharge or exit filter is used in place of airoutlet port 1222.

Pressurized, dry, filtered air is required in order to preventcontamination and moisture from entering the motor. A Pall PFD Filterused in combination with the pressurized air systems described hereinprovides a one-way valve with moisture and volume control if thepressurized air is discontinued. Such a combination also maintains thecleanliness of the motor.

Referring to FIG. 16, there is shown an alternate embodiment of motor1000 shown in FIG. 15A. Motor 1000′ includes all of the components ofmotor 1000 in FIG. 15A with the addition of external manifolds 2000 and2002, and air outlet vent filter 2004. External manifolds 2000 and 2002are located as required to move air and water into and out of motor1000′ as previously discussed herein for heating, cooling, andcontrolling moisture and volume. Although two external manifolds areshown, it is to be understood that more than two external manifolds canbe used.

External manifolds can be used in several of the foregoing embodimentsin order to satisfy motor thermal design requirements. For example, inthe embodiment shown in FIG. 15B, motor 1200 can be modified by addingone or more external manifolds.

The external manifolds can be used to deliver air or water into thecooling tubes or ducts in the motor at any point of entry and be usedwith any combination of the continuous cooling tubes or ducts describedin the foregoing description.

Referring to FIG. 17, there is shown motor 3000 in accordance with analternate embodiment of the present invention. This embodiment utilizesVortec air-amp cooling. Motor 3000 comprises casing 3002, top cover3004, bottom cover 3006, a rotor (not shown), a stator (not shown) and arotatable shaft 3008 which is connected to the rotor. This embodimentprovides dry, filtered cool air to the motor cavity via the expansion ofair through the Vortec device from a compressed air source. Adapter 3010is connected to motor casing 3002. An air amplifier device 3012 isconnected to adapter 3010. Air tube 3014 is connected to air amplifierdevice 3012. Air tube 3014 extends outside fan stack 3016. Fan stack3016 is only partially shown in FIG. 17. A complete fan stack is shownin FIG. 1. An air inlet filter 3018 is connected to the end of air tube3014. A suitable air inlet filter is the Grainger PN 3TLA5 inlet filter.Cool dry air 3020 enters inlet filter 3018, flows through tube 3014,through air amplifier device 3012 and into the motor cavity wherein itmixes with the air in the motor cavity so as to provide heat transfer,moisture and volume control. As the input air is heated by heat transferprocess, it exits the motor cavity by at least one outlet filter 3022.In one embodiment, outlet filter 3022 is mounted on top cover 3004 asshown. In another embodiment, the outlet filter 3022 is located outsidethe fan stack and a pipe routes the discharged air from casing 3002 tothe outlet filter. In another embodiment, a Pall PFD Filter is used incombination with inlet filter 3018. The Pall PFD Filter includes therequired valve arrangement that prevents contamination and moisture fromentering the motor through inlet filter 3018.

Referring to FIGS. 18A and 18B, there is shown a stator 4000 inaccordance with another embodiment of the invention. Stator 4000comprises a plurality of lamination sheets 4002 that are bonded orattached together to form a stator stack 4003. Stator stack 4003 hasslots 4004. Stator 4000 includes windings or coils 4006 that are woundabout stator stack 4003. Coils 4006 include end turns 4007. Stator 4000is pinned or attached to the interior wall of casing 4010. Stator 4000is includes serpentine cooling tubes 4008 that can transfer air, waterand other fluids (e.g. ammonia) through the motor to cool or heat themotor. Serpentine cooling tubes 4008 are embedded into windings 4006.Stator 4000 can be configured with a single run or multiple run ofserpentine cooling tubes or ducts throughout the stator stack 4003. Theserpentine cooling tubes can be routed throughout the motor based on thethermal requirements of the motor. In other embodiments, any suitableconduit of any cross-sectional shape may be used in place of roundtubes. Suitable materials for fabricating the serpentine cooling tubesare materials that have high thermal conductivity for heat transfer andacceptable electrically insulating properties. Such materials includeSilicone, Teflon and other high temperature plastics. Copper andstainless steel are suitable choices only when the motor components(e.g. windings or coils) are sealed and insulated such as by VacuumPressure Impregnation (VPI). If Silicone and Teflon are used to form theserpentine cooling tubes or ducts, then the stator windings need not beVPI-processed and the serpentine cooling tubes or ducts may be nesteddirectly in the windings. Silicone or Teflon serpentine cooling tubes orducts are electrically insulated and offer excellent thermalconductivity to transfer heat away from the windings, prevent damage tothe rotor and the magnets, and maintain thermal balance within the motorfor proper and efficient operation. Since the motors in the foregoingembodiments are sealed to prevent contamination and manage moisturewithin the motor, VPI processing is not required. When VPI processing isnot used, or when VPI coatings are removed from the windings, Siliconeor Teflon serpentine tubing or ducts provide significantly improvedthermal management.

In one embodiment, the serpentine cooling tubes are run into 180 degreeunions located and fixed in the motor to allow them to expand andcontract similar to straight tubes.

In alternate embodiments, serpentine tubing or ducts made from stainlesssteel or copper are insulated with an insulating wrapping material andthen wound with the stator coils. Then, the serpentine tubing or ductsand stator coils are then VPI processed.

In an alternate embodiment, serpentine tubing or ducts made fromstainless steel or copper are wrapped in a thermally conductive andelectrically insulating coil wrap. One suitable coil wrap is the ArlonSFT Self Fusing Tape.

In alternate embodiments, fluid inlet and outlet taps are utilized toconnect tubing or duct sections formed in the coil to create a coolingcircuit in the motor. The motor may have more than one cooling circuit.

In an alternate embodiment, serpentine cooling tubes or ducts can beused to contain a phase transfer medium.

In an alternate embodiment, the serpentine cooling tubes or ducts areconfigured with holes so that the serpentine cooling tubes or ducts cantransfer clean, dry, filtered air to the motor.

Referring to FIGS. 19A and 19B, there is shown motor 5000 in accordancewith another embodiment of the present invention. Motor 5000 employs aforced-water cooling scheme. The motor 5000 comprises casing 5002, topcover 5003, bottom cover 5004, stator 5005, rotor 5006 and rotor shaft5008. Rotor 5006 includes permanent magnets 5009. In this embodiment,stator 5005 has the same configuration and structure as stator 705 inFIG. 12A. Thus, stator 5005 includes cooling tubes 5010 that have thesame shape and configuration as cooling tubes 710. Stator 5005 comprisesa plurality of lamination sheets that are stacked together to formstator stack 5012. Cooling tubes 5010 are embedded in stator stack 5012as windings 5014 are inserted. Motor 5000 further comprises acircumferentially extending upper fluid manifold 5016 that is attachedto or integral with top cover 5003. The top openings of cooling tubes5010 are in communication with upper fluid manifold 5016. Fluid manifold5016 includes fluid inlet 5018 so that fluid (e.g. water) can bedelivered to upper fluid manifold 5016. The motor 5000 further comprisescircumferentially extending lower fluid manifold 5020 that is attachedto or integral with bottom cover 5004. The bottom openings of coolingtubes 5010 are in communication with lower fluid manifold 5020. Lowerfluid manifold 5020 has fluid outlet 5022 through which fluid exits.During operation, pressurized fluid (e.g. water) from a cooling towersource is delivered to fluid manifold 5016 via fluid inlet 5018. Thefluid passes through cooling tubes 5010 and absorbs heat from the statorwindings 5014. The heated fluid then passes out of cooling tubes 5010and into lower fluid manifold 5020 and wherein it is then dischargedthrough fluid outlet 5022. In a preferred embodiment, the fluid that isinputted into upper fluid manifold 5016 is filtered water. In apreferred embodiment, the water is obtained from the cooling towersystem. For example, in one embodiment, water from the cooling towerdistribution system is filtered and then inputted into fluid inlet 5018.The water that is discharged from fluid outlet 5022 is then recirculatedback into the cooling tower for cooling. In another embodiment, thewater discharged from fluid outlet 5022 is recirculated with a heatexchanger and exchanged with water drawn from a cooling tower source.Drawing water directly from the cooling tower eliminates the use ofconventional auxiliary cooling devices.

In alternate embodiments, cooling tubes 5010 are replaced with conduitshaving cross-sectional shapes other than round. In an alternateembodiment, cooling tubes 5010 are replaced by cooling ducts.

Rotor 5006 includes fan structures 5100 and 5102 which have the samestructure, function and purpose as fan structures 850 and 852,respectively, that are shown in FIG. 13A and described herein.

The embodiment shown in FIGS. 19A and 19B may incorporate thermostats,valves, sensors and solenoids to automatically adjust the watertemperature in the motor. In an alternate embodiment, heated water ispassed through cooling tubes 5010 in order to prevent the motor fromfreezing. Such an embodiment is suitable for use in geographical areasthat experience very cold temperatures. In one embodiment, theembodiments shown in FIGS. 19A and 19B may be used with the controlsystem described in international application no. PCT/US2012/061244entitled “Direct Drive Fan System With Variable Process Control” andpublished under International Publication No. WO 2013/059764.

In a preferred embodiment, the cooling tower water is used with a heatexchanger so that the closed loop fluid circulated in cooling tubes orducts can be mixed with an anti-freeze as required for cold service. Ina further embodiment, the pressurized hot water returned from theprocess can be combined with the pressurized return of cooler water fromthe basin feed to the process to provide a suitable temperature viamixing valves and thermostats. A third make-up water source can be usedas required to provide a suitable temperature to the motor (hot or cold)to maintain optimum motor efficiency through various environmentalconditions and process loads similar to an automobile radiator andthermostat.

Referring to FIG. 20A, there is shown another embodiment of the presentinvention. In this embodiment, a motor stator comprises a cooling tube6000 that is wrapped with individual stator coils 6002 or coil bundlesand disposed in the slots of the stator lamination stack. The view shownin FIG. 20A is that of a cooling tube 6000 wrapped with stator coils6002. In such an embodiment, heat is transferred from coils 6002 to thecooling tube 6000. Tap riser 6004 delivers air, gases and/or fluids (orcombinations thereof) to cooling tube 6000. Tap riser 6004 is insulatedfrom the electric circuit by isolation stack 6006. Cooling tube 6000 maybe made from copper, aluminum, silicone, Teflon or equivalent, and maybe part of the motor's electric circuit or insulated from the electriccircuit. The entire assembly (e.g. cooling tube 6000 wrapped with coils6002) can be potted and insulated as required using a manual or VPIprocess. Solid tubes, gas and liquid filled tubes can act as heat sinksand work with the heat-pipe embodiments described in the foregoingdescription. If cooling tubes 6000 are made from materials that are notelectrically conductive, then isolation stacks 6006 are not required.Such non-electrically conductive materials include Teflon and Silicone.Cooling tubes 6000 may be used to transfer air, gasses, water, fluids orcombinations thereof for cooling stator coils and for heating the coilswhen the motor is used in cold environments. In an alternate embodiment,cooling tubes 6000 contain a phase change transfer medium.

In alternate embodiments, cooling tubes 6000 are replaced by coolingducts, described in the foregoing description, or any other conduithaving a different cross-sectional shape.

FIG. 20B is an alternate embodiment of the configuration shown in FIG.20A wherein the cooling tubes 6000 are isolated from the electriccircuit of the motor. In this embodiment, an isolation layers 7000 and7002 are thermally conductive. Stator coils 6002 are wrapped aboutisolation layer 7000 and cooling tube 6000. An additional isolationlayer 7002 is wrapped about stator coils 6002.

Referring to FIGS. 21A, 21B and 21C, there is shown an alternate motorembodiment of the present invention. The motor 8000 comprises casing8002, top cover 8004, bottom cover 8006, stator 8008, rotor 8010 androtatable shaft 8013 that is connected to rotor 8010. Rotor 8010includes permanent magnets 8011. Stator 8008 comprises a stator stack8009 that is formed by a plurality of lamination sheets as described inthe foregoing description. Coils 8012 are wound about stator stack 8009.The motor 8000 further comprises a plurality of heat pipes 8020 that areembedded into coils 8012 and end turns of the coils 8012. Heat pipes arewell known in the industry and are therefore not described in detailherein. The heat pipes 8020 remove heat from the motor and ejected it tothe surrounding fan stream which is comprised of significant mass airflow of 100% humid air by design in wet cooling towers. Heat pipes 8020can be positioned so some of the heat pipes 8020 extend upward and otherheat pipes 8020 extend downward as shown in FIG. 21A. In one embodiment,50% of the heat pipes 8020 extend upward and the remaining 50% of theheat pipes extend downward. In one embodiment, the heat pipes 8020 arearranged so that every other heat pipe 8020 extends upward and theremaining heat pipes 8020 extend downward. In one embodiment, a heatsink 8030 is attached to each heat pipe 8020 as shown in FIGS. 21A and21C.

Rotor 8010 includes fan structures 8100 and 8102 which have the samestructure, function and purpose as fan structures 850 and 852,respectively, that are shown in FIG. 13A and described herein.

Heat pipes can be combined with at least some of the other foregoingembodiments, such as the aforementioned serpentine cooling tubes forremoving heat out of the motor. Heating pipes of any orientation andcombination and could be located further into the fan air stream.

In another embodiment, the motor comprises chill blocks that are incontact with the end turns of the windings. In such an embodiment, theheat pipes are embedded in the chill blocks.

The foregoing embodiments allow for thermal management of the motor inthe cooling tower. Thus, if motor performance begins to degrade, thepresent invention allows for changes in the thermal management of themotor to improve or maintain performance. This allows each motor in eachcooling tower to be optimize for thermal conditions. The ability tothermally manage the motor also facilitates maintaining a desiredrotor-to-stator gap (e.g. 0.030 inch, 0.060 inch).

Cooling tubes and heating pipes discussed in the foregoing descriptioncan be relatively small in diameter and can be embedded into coils,thermally conductive potting in the gap between the stator and the motorcasing, rotors and other motor structure during or after winding thecoils on the stator. Motors may be designed to allow room within themotor for routing tubes, pipes, ducts and serpentine cooling tubesthrough the motor, without being embedded into the coils, and throughthe slots where “slot fill” is typically applied. The term “slot fill”refers to empty volumes in the motor which are not taken up by windingsor coils and are therefore not part of the electrical circuit in themotor.

In an alternate embodiment, a water plenum is integrated with the motorcover (e.g. top cover) to provide cooling tower water for cooling themotor. The cooling tower water can be fed into any of the foregoingcooling tubes, ducts, serpentine tubes and ducts or any combinationthereof. The use of the cooling tower water that is readily availablefrom the header simplifies the cooling process and avoids the use ofsecondary auxiliary pumps, valves, controls and skids which can becostly and add significant weight to the cooling tower.

In any of the foregoing embodiments involving forced water cooling, thewater exiting the motor can be recirculated, or discharged in whole backinto the cooling tower, or mixed with new water, as required accordingto the heat transfer characteristics and the conditions under which themotor must operate. Such configurations also facilitate heating themotor in very cold climates to prevent the motor from freezing.

In other embodiments, mixing valves and control devices can be used tomaintain predetermined water temperatures according to motor operatingparameters, water temperature and environmental stress in order tooptimize motor efficiency.

In other embodiments, a closed Glycol loop or equivalent and a heatexchanger device is used to provide cooling water, air, ocean water orother medium to cool the motor.

It is to be understood that many commercially available surfacetreatments and chemical compounds may be used on the components of themotors of any of the foregoing embodiments of the invention in order todissipate heat or retain heat as certain locations within the motor.Such surface treatments and chemical compounds include thermal barriercoatings, thermally conductive epoxies, epoxy resins, thermallyconductive potting, thermally conductive insulators and heat dissipationcoatings.

All of the motor embodiments disclosed herein may be used with orcontrolled by the control system described in international applicationno. PCT/US2012/061244 entitled “Direct Drive Fan System With VariableProcess Control” and published under International Publication No. WO2013/059764.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated

What is claimed is:
 1. A cooling tower comprising: a cooling towerstructure; a motor supported by the cooling tower structure, the motorcomprising a motor casing and a rotatable shaft; a cooling tower fancomprising a fan hub and a plurality of fan blades attached to therotatable shaft; a supplemental fan attached to the fan hub such thatthe supplementary fan is between the fan hub and the motor; wherebyrotation of the cooling tower fan causes rotation of the supplementalfan which increases airflow around the casing of the motor.
 2. Thecooling tower according to claim 1 further comprising a fan pitchadjustment device to adjust the pitch of the supplemental fan.